GARDEN FRIENDS. 



121 



aphis, or other form of insect life, has one or 

 more parasites which keep it in check, sometimes 

 with more certain effect, and always with more 

 persistent action, than by human agency. Not 

 even wireworms en- 

 joy immunity. These 

 ichneumon flies, their 

 maggots and pupae or 

 cocoons, as the case 

 may be, when observed 



and recognized, Should Fig.l56.-Ichneumon Flies (magnified). 



be spared or exempted 



from destruction where possible to avoid them, 

 while artificial measures are being employed to 

 destroy the caterpillars or other plant enemies. 

 None of the latter attacked by an ichneumon ever 

 reaches the perfect state. No gardener, unless 

 he is specially versed in entomology, can ever 

 hope to recognize or determine the species of 

 parasites that thus befriend him, but he may 

 often, by close observation, obtain conclusive 

 proof that certain insects are parasites by their 

 behaviour during the process of laying their 

 eggs in caterpillars or in aphides. The latter, 

 in some species at least, recognize their enemy, 

 and throwing up the hinder part of their body, 

 sway from side to side as if to cast off the in- 

 sidious parasite or keep it at bay. In size the 

 grub of the parasite bears some relation to the 

 size of the host in which it has to feed, so that 

 th,e grub infesting green-fly must be very small. 

 The ichneumon infesting the Death's-head Moth 

 is the largest British species in the family. 

 Scientific men have long recognized the value 

 of parasites in keeping certain insects in subjec- 

 tion, and now transport them long distances, 

 even to the antipodes, where they place the 

 parasites to feed and breed amongst insects that 

 infest fruit plantations. 



Lacewing Flies. — There are four genera 

 of these flies, constituting a family of insects 

 whose larvae are very voracious, devouring 

 aphides in large numbers. It has also been 

 observed that they will attack caterpillars f inch 

 long. Some of them are curious-looking crea- 

 tures, furnished with a row of protuberances 

 along each side, with a tuft of bristly hairs on 

 each tubercle. They vary in colour from 

 whitish to pale -brown, with brown or orange 

 spots. Some cover themselves with the skins of 

 the aphides which they have seized and sucked 

 dry, and others cgnceal themselves from birds 

 by means of lichens. They are so destructive 

 to the colonies of aphides amongst which they 

 reside that they have been named aphis lions, 

 a title they well deserve, for they never cease 



to hunt after and devour the helpless aphides 

 till full-grown, when they change to pupae and 

 reach the perfect state in three weeks during 

 the summer months, while those that do not 

 attain their full growth till autumn hibernate 

 in the pupa state till spring. The cocoon which 

 the larvae spin from the tail end is made of 

 extremely tough silk, and varies in size from, 

 that of a grain of barley to that of a pea. There 

 are about ten or a dozen British species of 

 Chrysopa, and ft perla may be taken as a type 

 The wings are twice the length of the body 

 pale-green, but giving other beautiful reflections, 

 and finely netted, like a piece of extremely fine 

 lace; hence the name of lacewing flies applied 

 to the group. The eyes are golden-green, very 

 large and conspicuous, so that by them, the 

 characters already given, and the slender, jointed 

 horns equalling the body in length, they may 

 readily be recognized by those even who are 

 not entomologists. They fly chiefly by night, 

 but may often be seen lying lazily upon the 



Fig. 157.— Lacewing Fly. 



1. Chrysopa perla. 2. Eggs. 3. Larva. 4. Larva magnified. 5 and 6. Co- 

 coon (natural size and magnified). 



branches of Apples infested with American 

 Blight, and upon other trees, during the day. 

 The female is J inch long, and larger than the 

 male. The eggs are laid singly on hair-like 

 stalks in rows or clusters, sometimes projecting 

 an inch from the surface of leaves or branches 

 to which they are attached. Thus the group 

 of lacewing flies may readily be recognized in 

 all stages of their existence, and should be 

 religiously protected as the best friends of man 

 in gardens and orchards. The larvae may some- 

 times be found in company with those of the 

 hawkflies and ladybirds, all intent upon the 

 destruction of the aphides. 



Slugs. — Some of the more common species 

 of slug have already been described as enemies 

 of cultivation, and such they will ever remain ; 

 but there is a genus of slugs that are entirely 

 carnivorous, feeding upon worms, sometimes of 

 considerable size, and also upon the slugs that 

 live upon vegetation, and often prove xevy 



